Variable displacement pump unit



March 13', 1956 A. P. SMITH VARIABLE DISPLACEMENT PUMP UNIT qu LL] Filed June 6, 1952 ATTV March. 13, 1956 A. P. SMITH VARIABLE DISPLACEMENT PUMP UNIT 4 Sheets-Sheet 2 Filed June 6, 1952 March 13, 1956 A. P. SMITH VARIABLE DISPLACEMENT PUME UNIT 4 Sheets-Sheet 3 Filed June 6. 1952 ATTY March 13, 1956 A P, SMH-H 2,737,900

VARIABLE DISPLACEMENT PUMP UNIT Filed June 6, 1952 i 4 Sheets-Sheet, 4

ATTV

United States Patent 2,737,900 VRIABLE DEPLACEMENT P'rnvi) Unir Albert P. Smith, Mountain Grove, Mo.

Application June 6, 1952, Serial No. 292,139

4 Claims. (Cl. 10S-1162) This inv'entic'vn relates generally to hydraulic transmissions and is directed particularly to a transmission of'suc'h type which is piston operated.

A principal object of the present invention is to provide an improved variable displacement pump iinit for use in a hydraulic transmission mechanism, as hereinafter more 'specilically pointed out, wherein by means of 'opposing driving and driven piston u nits rotary power transmitted in varying degrees of speed from a drive sha'ft 'to a driven shaft. v

Another object of the invention is toprovide, in a manner as hereinafter Vs et forth, a variable displacement lpump jnit for `lise in a hydraulic transmission ,mechanism ernploying opposing reciprocating pistons Vwith control means for varying the extent of travel of the pistons `whereby rotary power may be transmitted from Vthe'drive vshaft to the d'rfive'n shaft in smoothly vcharigirigincrerrifents from Hneutral o'r stationary position tovmaxirnurn 'speed position.

variable displacement prnpy iinit of lthe "character above centrifgally V operated governor niean's which "as fthe i'cre'singl of power and speed in the d en pistons and whichftlie'y are j'connec'ted.

the driven shaft with ft of the invention is to' provide, in

A itin infine; ein

,a mnner as hereinafter set forth, nid bypas'sfrneais coin'e app'r''nt 1as vthe description ofthe jsaine proceedsand )the invention will behest understood fiom'a consideration ofthe following detailed descriptiontaken in onn'eciion withftliefaecinpanying 'drawings' formin'ga part of the specication, with thejunder'standingjhowever, that 4'the in- 4vt'entn is not Yto be limitedto the :diaet details if construction shown and describedisinceohvions inodiiications will ccc'nr to a person skilled in the art.

n; i drawings: I Figure' ris a view partly 'iiil elevation aia iiy iii liifgittldinl Section f avfll'lid transmissionconirhctdin accordance fwith the present invention;

Figure 2 a' central longitudinal lsection taken Isnli'st'antially on the line 2-2`of Figure l.

is aviw in'elevatio'nfthe 'control ring, a portion be'nigmbike away.

2 Figure E isa Idiagra niniatie view illustratin'githe of the adjacent 'interengaging teeth` between a swashplate and lan encircling ring gearand illustrating-the-nianner in which the swash plate teeth engage the ring-gear teeth. Figure 7 is a 4face 'view of one o'f the control valve hosings.

Referring now inforeparticularlyfto the drawings the numeral '10 generally designates a drive shaftto which power 4is applied by any' suitable means, 4not shown, while thedrivenshaft, which operatively coilpled with the transmission mechanism aboilt to be described, is Vlgenerally designated 12. A,

In accordance 'wit'htlie'presentinventidr the rear'eiidof the Adrive shaft u10 Vis enclosed in and extends V'axially ihriigh firel cyiiii'dricai diiviiigmiii neu ,16 iiiiihkjis closed at its outer end bythehead 418, secnredby snitble cap screws 20 to the out turned ange portion 1'6'11 of ihesheuns. p y y The ,centerof the head 18 has 'an opening 22 through which the shaft passes Eind pon Athe inner sjide ofthe head is a bearing race 24 in which is positioned the antifrict'io'n or bearing unit which'is generally designated 26 and through which the shaft Apasses and in which vit 4is snppr t"e'd I The ineieiipi or iii'ejs'heii i's'hasih'e iiiiiiriiedinnige 161i whichfis positioned einst neface of the circnlar divisien wan which is 'geneiaiiy 'designated zs and "ij wiiifeh 'ii is'secn'red by cap screws 3'0 which pass through 'the-Harige 16bintothewa1l wall 23 has in its two oppositefacs th'e'oppdsitely directed bearing 'recesses 32 'in wh'ich are mounted the anti-frati@ uiiiis siiids "shawn, iiie unit 34 'wiiih is directed intofth Shell f6 has the ir vend of :die drive Shania siepiiiiiierin,

Upon the opposite Siae df ine ai'vision 'vvau 2s is; a c :ylindrical `shell 36 of the saine character as the shell 1`6 and 'censiiiuiiiig the driven iinii siren qi hanging. This 4shell 36fhs at its forward eridthe inturnefd `lianger3i8 which bears against the' adjacentifa'ce 'of the division wall 28 and is s ecured,thereto bycap screws 40V ile at 'the 'enter end the vshell ilhasltheiollt t'rned ange T he numeral designates the driven riittvshelllifd Whiii is Asebi-inizi i6 fire "iiiigem 'b'y screws. 43, rn file center of the h'ed `42v i's a 'shaft peiiifig 44 leading lino the inwardlydirectedilange 45 which is concentric lwith deepening '44 'afidwiiinpoide's a cup for 'iiien'ring riait-46. p

The iiriviijshafi 12 iein as ihrpiigh the 'peiiiii'g "44 is snpported the lbearing unit i6 and liasits inner or forward endA stepped as shown in the adjaeenthantifriction or bearing unit 34 carried by thewall From the foregoinggit will be Vseen Vthat the shafts 10 and `12 are maintained in end aligned relation 'and are supported for independent rotation within their respective shells or housings.

The division Wallj28 between ttheslivells v15 'an'dj' isprovided wiih "the 'ivvo concentra-ally *arranged cirular or a'rcate Huid t'rans'fer chambers '47 :aride A, 'of these chambers is outlined by :a Acontin'ons 'channel d'8' Ain which is positioned a sealing ring 49 of a suitable frie'tal lsuch as cast iron', bron-zocor the'likvetwhich egtendsoutwardly beyond thev adjacent face' of'the'wall'28, for the prpose hereinafter set forth.

Within the driving Unit Shell 1'6is eirolfllr cylinder block which is generally designatedll. Thisbloclr has formed therein around the'arrial center thereof the vcircularly arranged series of ailially directed piston cylinders 51 whichopen through the innerl end, of the bloclg aS shown 'while the outer ends of 'such cylinders open into thei circular chamber 52 which is formed in the outer end of the block and which is defined by the circular wall 53.

The chamber 52 opens into or has formed in the central part thereof within the circular area dened by the series of cylinders 51, thewcentral circular pocket 54 which is provided for the purpose hereinafter set forth.

The central part of the circular cylinder block provides a hub 55 through the center of which is formed the shaft opening 56. The inner portion of the shaft extends through this opening 56 and is secured to the hub by the key 57 or in any other suitable manner. Thus it will be seen that the cylinder block Sil is secured to the shaft 10 to turn therewith and the inner end of the block bears against the adjacent packing 49 which encircles the uid transfer chambers and it will also be seen that the centers of the cylinders are arranged in an arc or circular path which lies in the center of the arcuate fluid transfer chambers. Also the diameters of the cylinders is not greater than the width of the iluid chambers so that the packing strips at the inner and outer sides of the chambers will lie outside of the cylinders to prevent leakage of uid from the cylinders between the cylinder block and the adjacent face of the division wall 28.

Lying within the pocket 54 is a plate 58 which carries on the face directed away from the hub 55, a pair of pivot ears 59. This plate is of annular form and encircles the shaft 10 as shown and in opposed relation with the plate 58 and spaced therefrom is a coacting outer plate 60 which encircles the shaft 10 and which carries an outwardly extending sleeve 61 which surrounds the shaft.

The inner face of the plate 60 carries a pair of ears 62 which are in opposed relation with the ears 59 for cooperation therewith in the manner about to be described.

Each pair of opposing ears 59-62 carries a centrifugal weight unit which comprises an arcuate arm 63 having an end pivoted to the adjacent ear 59 and a link 64 having an end pivoted to the adjacent ear 62 and having its other end pivotally connected to the arm 63 as indicated at 65. As shown each arm 63 extends outwardly beyond the adjacent link 64 and carries on its outer end a weight member 66.

Encircling the shaft 10 and interposed between the plates 58 and 60 is a coiled expansion spring 67 which constantly urges the outer plate 60 away from the inner plate 58 and consequently tends to draw the centrifugal weights 66 inwardly.

Encircling the shaft 10 between the head 18 and the outer end of the cylinder block 50 is a control ring 63 in which is xed the annular bearing unit 68.

The control ring 68 has formed integral therewith the radially extending arm 69, for the purpose hereinafter described.

The numeral 70 generally designates a swash plate which is centrally apertured and carries the outwardly projecting hub 71 which has the conical passage therethrough through which extends the sleeve 61. As shown the narrow end of the hub passage 72 is toward the inside of the machine or adjacent to the plate 16.

The hub 71 is fitted to the inside of the bearing unit 68 whereby the swash plate can rotate with the cylinder block while the control annulus or ring 68 remains stationary.

The control ring has at diametrically opposite sides and in a line perpendicular to the radial line of the arm 69, radial arms 73 which terminate in the right angularly disposed pivot ears 73a which position adjacent to the inner sides of the shell 16, as shown in Figure l.

Threaded into the openings 74 in the said opposite sides of the shell 16, are the trunnions '75, each of which extends through an apertured ear 73a. Thus the control ring 68 is supported for turning movement on the aligned supporting trunnions 75 and as will be readily seen, when the control ring is turned on its supporting trunnions it will also turn with it the swash plate 70 which is in` a plane parallel with the control ring. K

Manual control of the ring 63 is provided by the rod 173 which extends longitudinally through the shell 36, I the division wall 28 and into the shell 16 and is in endf' alignment with the outer end of the control ring arm 69" as shown.

Within the shell 16 and encircling the free inner end of the rod 173 is a pull spring 174, one end of which is secured to the rod 173 as at 175, while the other end iS secured to the outer end of the arm 69 as indicated at 176.

The periphery of the swash plate 7i) has formed therearound the spaced teeth 77 which are tapered from the transverse center toward the front and rear edges as illustrated in Figure 6. The function of these teeth is hereafter described.

inwardly of the annular series of teeth 77 the swash plate '70 has formed therein the circular series of sockets 78 equaling in number the adjacent piston cylinders 51 and in each of these sockets is positioned the spherical or ball end 79 of a connecting rod Si).

The other or inner end of the connecting rod 80 has a similar spherical head S1 which is secured in a piston S2 slidably positioned in an adjacent cylinder 5l.

Positioned against the inner face of the swash plate- 70 and secured thereto in any suitable manner is a retaining plate 76 which engages the heads 79 of the connecting rods to maintain the heads in their sockets 78.

The numeral 83 designates a ring gear which is secured to the outer end of the annular wall 53 as shown and which has the internal teeth 84. This ring gear 83 is of an inside diameter to receive the annular series of swash plate teeth 77 which t between the teeth 84 of the ring gear. As will be readily apparent since the swash plate 70 turns on an axis which passes diametrically through the ring gear, certain of the swash plate teeth will be at all times connected between the ring gear teeth and as the plate swings on its axis into a common plane with the ring gear 83 more of the teeth of the plate and gear will come into mesh until, when the plate and gear are in a common plane all of the teeth upon the two members will be engaged.

Within the driven unit shell 36 there is positioned concentrically with the driven shaft 12, a circular cylinder block 85 corresponding to the cylinder block 50, in which are formed the series of piston cylinders 86 corresponding in number to the cylinders 51.

The outer end portion of the block 85 is chambered as indicated at 87, whereby is formed the circular wall 88 and the cylinders 86 open into the chamber portion 87 and at their inner ends open through the inner end of the block, which end is positioned against the annular packing rings 49 in the same manner as the block 50.

The central portion of the block 85 provides a hub 89 having the bearing opening 90 therethrough through which extends the shaft 12.

As illustrated the end of the shaft 12 which is adjacent to the bearing unit 34, is keyed, as at 91, to the hub 89 so that rotary movement imparted to the block 85 will be transmitted to the shaft 12.

Encircling the rear end portion of the shaft 12, within the shell 36 and adjacent to the head plate 42 is a ring 92 corresponding to the ring 68, which carries the diametrical arms 93 which terminate in the mounting ears 93a. These ears 93a are mounted upon pins 94 xed in the wall of the shell 36. The ring 92 is maintained in a plane oblique to the shaft 12, as shown, by suitably positioned stops 92a carried upon the inner face of the head 42, as shown in Figure 2.

The forward or inner face of the ring 92 is recessed as at 95 to receive the annular bearing unit 96, in which unit is secured the hub portion 97 of a swash plate 98. This hub and plate has the conical opening 99 there- 7djaciit'hoiising wall to communicate with the interior "'f the" housing in which is encased the cylinder blockpis- "'to'n's and other units. ln other words one end chamber lil Ico'mnilnicat'es with the interior of the cylindrical shell while'the' other end chamber 111 of each valvev housing 108 communicates with the interior ofthe shell 16.

` The central chamber 109 of'each valve housing 108 is i'i-iirf communication -with -the ltwo adjacent end chambers l-11-1 throgfhthevalve-port 113A and these valve ports are provided on corresponding sides with the annular valve seats 114.

One of the end chambers 111 of each valve unit has a tapped opening therein as indicated at 115, in Which is threaded the guide collar 116 and through this guide collar extends a valve stem 117 which passes through the adjacent end chamber 111 and through the central chamber 109 and carries the two valve disks 11S, each of which is formed to engage a seat 114.

The guides 116 are arranged corresponding ends of the valve housings 109 and the stems M7 extend through apertures in radially extending guide ears 119 carried by the head plate 42.

Suitable means is provided, not shown, for effecting the movement of the rods 117 for unseating or seating the valve disks 118 and also suitable means, not shown, is provided for effecting the actuation of the rod 73.4

In the operation of the transmission mechanism the shells 16 and 36 are iilled with a suitable fluid which also fills the transfer chambers 47. When rotary motion is applied to the drive shaft such rotary movement will be transmitted to the cylinder block 50. During the stationary period of the transmission mechanism the spring 67 will force the swash plate 70 and control ring 67 to turn to a position in a plane perpendicular to the drive shaft thus pulling the centrifugal weights 66 inwardly. During such self adjustment of these parts under the action of the spring 67 the pull spring 74 will be stretched and put under some tension.

As the speed of rotation of the shaft 10 and block 50 increases the centrifugal force will move the weights 66 outwardly, such weights being connected through the medium of the arms 66 with the plate 58 which is secured to the block and this will retract the plate 60 which is pressing against the swash plate 70 thus permitting the pull spring 174 to turn the control ring 68 on the supporting trunnions 75.

The spring 74 will continue to move the control ring and swash plate 70 to the extent permitted by the centrifugal weights or bythe rearward movement of the plate 60 under the pull of the weights whereupon the swash plate will remain at the selected angle to the drive g "ITan'd encircling the wash plate and'secured to @afrit-laaste r cylinder .block to v j Y the" connecting gear teeth `7 7 and '84" the diviigl "pi'sfns 82 will be moved in and out in their cylinders as be readily apparent. n I j 'As eaclipiston 82 moves outwardlvrfaway fm'the adjaeer'ithfluidv transfer chamber'ilu'id will be4 dr'a'vvniii'to the cylinder from the Yopposing cylinder^86"and reverse the opposite cylindersojas 'to 'fo'rtle `Sippsite cylinder -107'therein` outwardly theebyftrans'mittiiigpressure to ther plate 98 to cause'sueh'plate'to tate'and thereby transmit corresponding ,rotation tejfne'cynndblockss tlir'onglithe interconnecting teeth '100' and 102.

'It ivillbe understood, of course, that duringftlie operation abovev described the valves118 will be closedso that iuid in the transfer chambers '47 will beretained` erein and in the' piston' cylinders opening into sch chambers.

l If itjsho'uld'be desired4 t'olslov/upithe rotation-ofthe driven 'shaft the valve stems 'V117'will beshiftefd topn thevalve 'members 118 or 'disengage them fromV their seats 114 so that the 'fluid in the transfer chambers will be permitted totlow into a'nd out lof the Vshells 16 and 36 ias the pistons [reciprocate and the driving force'against tlie pistons 107 will be reduced or stopped entirely. VThus Vit willbe seen thatthe powertransmittedto the driven lshaft "12 'from the` drive shaft canberegulatedwithout having" tore'duce thfe'spe'ed of operation of the engine operating the drive's'haft. j l j j l 'twill alsobe 'apparent'that `byadjusting the rod'173 the "pull ofv the spring '174 uponthe control diskGScan be increased or ligh'teed as desird 'to thuselfect 'the desired angular adjustment oftheiswashzplate 70.

If it is desired to reverse the direction of rotation of the driven shaft 12 such reversal is accomplished by shifting the rod 173 inwardly to bring the inner end against the extension 69 of the control ring 68 to thereby oscillate the ring 68 from the position in which it is shown in Figure 2 to a reversely disposed angular position or, in other Words, to'a position in which it is oblique to the shaft 10 with the extension arm 69 inclined toward the front. This reversal of the oblique disposition of the control ring will shift the lowermost piston 82 rearwardly and shift the uppermost piston 82 forwardly in their cylinders with the other pistons in corresponding intermediate positions. Accordingly upon rotation of the cylinder block 55 the piston 32 which is at the uppermost position in Figure 2 will start to move rearwardly and the piston 82 which is lowermost in this figure will start to move forwardly to thereby apply pressure, together with the other pistons, in the reverse direction to that in which it was previously applied with a consequent reversal of the direction of rotation of the plate 98 and the cylinder block 89 connected thereto through the medium of the pistons and piston rods and 107.

I claim:

l. In an apparatus of the character set forth, a rotary cylinder block, means supporting the block for rotation, said block having cylinders extending lengthwise of its axis of rotation, piston members positioned for reciprocatory movement in said cylinders, a circular plate centrally traversed by said axis, means supporting the plate for both rotational movement around said axis and for rocking movement on an axis perpendicular to said rotational axis, piston rods operatively coupling the plate and said pistons, means for electing rocking adjustment of lthe plate between a position in which it is in a plane perpendicular to the first axis and a position in which it is in a plane oblique to the first axis, a gear coupling between the periphery of the plate and the cylinder block by which driving connection is maintained between the plate and cylinder block in all positions of adjustment of the plate, said block having an end provided with an open chamber, said plate being positioned to have a portion enter the chamber when rocked to an oblique position, and said gear coupling comprising an internal tooth ring gear carried by the block and encircling the plate and gear teeth carried by and around the edge of the plate.

2. The invention according to claim 1, with spring means interposed between the block and the plate and urging rocking movement of the plate to a position in which it lies in a plane perpendicular to the rst axis, and centrifugally actuated means connected to and rotatable with the block for retracting the spring means,

3. In an apparatus of the character set forth, a rotary cylinder block, means supporting the block for rotation, said block having cylinders extending lengthwise of its axis of rotation, piston members positioned for reciprocatory movement in said cylinders, a circular plate positioned to have said axis pass centrally therethrough, an annular member encircling said axis and having a radially extending arm, a pair of bearing arms carried by said member at diametrically opposite positions thereon, pivot members engaged by the bearing arms and supporting the annular member for rocking movement on an axis intersecting and perpendicular to the rst axis, an annular hub carried by the plate, a bearing coupling between said hub and said annular member by which the plate may rotate with the block, a plurality of piston rods each pivotally coupled at one end to the plate and having operative connection at its other end with a piston, means connected with the rst radial arm of the annular member for rocking the member and plate on the second mentioned axis, a coupling between the periphery of the plate t' and the cylinder block by which driving connection is maintained in all positions of angular adjustment of the annular member and plate with respect to the first axis,

said block supporting means comprising a shaft, a thrust member slidably positioned on the shaft between a part of the block and the plate and bearing against the plate, spring means constantly urging the thrust member toward the plate, and centrifugal members connected between the thrust member and the block and acting under centrifugal force to retract the thrust member.

4. The invention according to claim 3, wherein said cylinder block has an end provided with a chamber opening toward the plate and annular member, said plate being positioned to have a portion received within the chamber when the plate is rocked to an oblique position,

and said coupling between the periphery of the plate and the cylinder block comprising an internal tooth ring gear f secured to the said end of the cylinder block and lying in the plane of the axis of rocking movement for the annular member, and gear teeth carried by and around the edge of said plate, a number of which gear teeth are in constant mesh with teeth of the ring gear.

References Cited in the iile of this patent UNITED STATES PATENTS 225,651 Silver Mar. 16, 1880 765,434 Manly July 19, 1903 924,787 Janney June 15, 1909 1,539,616 Williams May 26, 1925 2,292,125 ltield Aug. 4, 1942 2,518,473 Hogeman Aug. 15, 1950 2,678,536 Morgan May 18, 1954 FOREIGN PATENTS 605,215 France Feb. 13, 1926 959,014 France Sept. 21, 1949 

